Level-wind structure



July 29, 1969 F. 1.. LAWRENCE LEVEL-WIND STRUCTURE 3 Sheets-Sheet 1 Filed June 28, 1967 FRANK L. LAWRENCE INVENTOR.

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ATTORN E Y5 July 29, 1969 F. LAWRENCE LEVEL-WIND STRUCTURE 3 Sheets-Sheet 2 Filed June 28, 1967 FRANK L. LAWRENCE INVENTOR.

ATTORNEYS July 29, 1969 F. L. LAWRENCE LEVEL-WIND STRUCTURE 3 Sheets-Sheet 5 Filed June 28, 1967 ER 5 CO H NT N m m V a 6 WN I A aim G K H m R F Y B 3 4 6 6 J III. 5 6 |l 2 3 WI 6 a X United States Patent 3,458,153 LEVEL-WIND STRUCTURE Frank L. Lawrence, Vancouver, British Columbia, Canada, assignor to Lawrence & Schild Ltd., a corporation of Canada Filed June 28, 1967, Ser. No. 649,635 Int. Cl. B65h 57/28; 366d N38 US. Cl. 242158 8 Claims ABSTRACT OF THE DISCLOSURE By far the majority of the level-wind structures heretofore devised have incorporated what is commonly known as a diamond screw drive to impart reciprocatory movement to a traverse head. Diamond-screw drlves Wlll not stand up under excessive thrust loadings such, for ex- I ample, as those to which the drums of a logging yarder are subject. The present invention aims to provide an efficient level-wind structure capable of withstanding high levels of torque loading, Which is not adversely affected where required to operate under adverse weather conditions, and which exhibits only minimal wear under long and continual usage.

In the accompanying drawings:

FIGURE 1 is a fragmentary side elevational view, with parts broken away and in section, to illustrate a yarder having a level-wind structure employing preferred teachings of the present invention.

FIG. 2 is a fragmentary top plan view thereof.

FIG. 3 is a fragmentary transverse vertical sectional view drawn to an enlarged scale on line 3-3 of FIG. 1.

FIG. 4 is a fragmentary enlarged-scale view detailing the control valve and associated mechanism shown in FIG. 3.

FIG. 5 is a fragmentary vertical sectional view drawn to an enlarged scale on line 5-5 of FIG. 3.

FIG. 6 is a fragmentary detail elevational view drawn to an enlarged scale; and

FIG. 7 is a fragmentary longitudinal vertical sectional view drawn to an enlarged scale on line 77 of FIG. 2.

Referring to said drawings, a fabricated frame-work for a yarder is designated by the numeral 10, and denoted by 11 is one of the several cable-winding drums usual to a yarder. A drive is passed by a chain 12 to the drum, and such drive desirably includes a reversible hydraulic motor (not shown) having its pump driven by a diesel engine or other suitable power plant. The cable C is led to and from the drum by passing through a hollow pib which extends longitudinally of the yarder, being trained over a respective one of two fair-lead sheaves 13 and 14 at each of the two ends thereof. The jib is universally journaled for both swing and swivel movement in the frame of the yarder by a ball-and-socket joint, the ball component 15 being formed upon the jib and the socket component being formed in part by a fixed ring 16 and in part by a removable keeper ring 17 which is bolted in place. The socket is located in the longitudinal median plane of the drum above and at a distance of say 12' or so therefrom. A long arm 18 of the jib extends inwardly toward the drum and overhangs the near side of the latter. A short arm 19 of the jib extends outwardly.

Patented July 29, 1969 Sheave 13 receives its mounting from the short arm, being journaled upon a cross-pin 20 in an offset position placing its perimeter tangent to the swivel axis of the jib The hollow stem of a block 23 is swivelled in the free end of said long arm 18. Sheave 14 receives its mounting from the block, being journaled upon a cross-pin 24 in an offset position placing its perimeter tangent to the swivel axis of the block.

The free end of the jibs long arm is attached by a pivot pin 25 to the upper free end of a powered third-order rocking lever 26 which establishes for said free end a reciprocating travel moving along a prescribed path the end limits of which coincide with perpendiculars raised from the two ends of the winding surface of the drum. In compensation of the compounded are along which the free end of the arm 18 travels, the rocker fulcrum for said lever 26 is a ball-and-socket, denoted at 28. The power for reciprocating the lever is a double-acting hydraulic jack 29 having one end pivoted at 30 to the frame of the yarder and the other end pivoted at 31 to the lever. A valve 32 governs the jack, the valve being of the usual character having a valve spool 33 working within a chest, with the particular end of the jack to which hydraulic fluid is fed and the rate of the fluid flow being determined in the respective instance by the positionright or left of centeroccupied by the spool and the degree of movement from said centered neutral location.

Such movement of the spool within the chest is regulated by means including a rotary cam 34, the cam being interconnected with the drum by a reduction drive so as to complete a half revolution while the drum is making the turns necessary to develop one full wrap of cable. The number of turns required for a full cable wrap of course determined by the cable diameter. In instances Where it may be desired to adapt the winding drum to different sizes of cable, it becomes necessary only to modify the reduction ratio and this is or may be accomplished by employing in the reduction drive an endless chain 35 trained over a selected one of several sets of sprocket wheel, as 36-37, each correlated to a given cable diameter. The reduction drive is here shown as including with the chain and its sprocket wheels, a pinion 40 meshing a gear wheel 41, and a pinion 42 meshing a gear wheel 43, the cam 34 being made to turn in unison with the latter gear wheel.

The profile configuration of the cam is so developed that a roller 45, carried by a third-order lever 46 and tracking on the perimeter of the cam, moves radially thereof at a uniform speed inwardly during one-half the turn of the cam and outwardly during the other half. The lever 46 is fulcrumed at 47 and acts through a rack-andpinion connection 50-51 to govern the rotation of a reciprocally movable sprocket wheel 52 serving a motiontransfer function. Attached by one of its ends to this sprocket wheel is a chain 53 taking a right-angle bight midway its length over a floating sprocket wheel 54 and having its other end attached to the rocking lever 26. The floating sprocket wheel is carried by a third-order lever 55 fulcrumed at 56 to the frame of the yarder and attached by a link 57 to the spool 33 of the control valve 32.

Spool 33 is shifted, against or with the applied force of a spring 60, in either a left-to-right or a right-to-left direction (as viewed from the vantage point of FIG. 3) for respectively causing hydraulic fluid to be charged to the right-hand end or the left-hand end of the hydraulic jack. Greater or lesser tensions of the chain are responsible and act upon the floating sprocket wheel to dictate the direction and the extent of the spools shift. When the rocking lever is moving in a left-to-right direction, the spool has moved left of center. An increase in the tension of the chain occurs should a volume of oil be supplied to the jack causing the rocking lever to over-run a predetermined position prescribed therefor for any given period of the cable-wrapping cycle. This increase of tension draws the spool toward center, which reduces the oil flow. A lag of the rocking lever when moving in said left-to-right direction decreases chain tension with a responsive spring-influenced movement of the spool from center, which increases the flow. When the rocking lever is moving in the opposite direction, namely right to left, the spool will have then been moved right of center. For this direction of travel an increase of tension occurs by a lag of the rocking leg, and a decrease occurs by an over-run. The spool shifts from center and toward center in the respective instance, which perforce causes an increase and a decrease, respectively, in the oil flow.

There is provided in the level-winding system a release means for the chain 53 which automatically slacks off the chain should the same be tensioned above a predetermined ceiling point. A situation in which this high tension could occur is where an operator, shutting down over-night, neglects to slack off the cable. Should the cable be left taut the possibility arises that a log, snag or the like laying against the cable at a point close-in to the yarder can exert upon the cable a lateral force of sufficient magnitude that the jib, responsively torquing about a vertical axis, snaps the chain. The release comprises a shoe 61 pivoted at 62 to the leg so as to rock about a horizontal axis extending transverse to the chain. The chain seats in a groove extending longitudinally of the shoe and is connected at 63 to the free end of a triplever 64 pivoted at 65 to the shoe. The trip-lever is yieldingly urged in a forward direction by a spring 68, catching under a lip 66 formed upon a bracket 67 welded to the rocking-leg.

It is believed that the invention will have been clearly understood from the foregoing detailed description of my now-preferred illustrated embodiment. Changes in the details of construction may be resorted to without departing from the spirit of the invention and it is accordingly my intention that no limitations be implied and that the hereto annexed claims be given the broadest interpretation to which the employed language fairly admits.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A level-wind structure comprising: a power-driven cable-winding drum, a carriage through which cable is adapted to be led to the winding surface of the drum, means guiding the carriage for reciprocal movement in a path transverse to the drum and extending from one to the other end limit of the winding surface, a motor drivingly connected with the carriage for operating the carriage in said reciprocal movement, a motion-transfer member mounted for reciprocation, a connection from the drum to said member causing the member to move in concert with the drum through repeating cycles of reciprocation changing direction when the drum has made the turns necessary to take a complete wrap of cable thereon, and inter-related connections between said member and both the motor and the carriage causing the motor to (1) reverse the direction in which it is driving the carriage when the member reverses its direction of movement, and (2) responsively increase or decrease the speed at which it drives the carriage when the carriage, in course of moving between its end limits of travel, lags behind or over-runs, respectively, predetermined points of progress correlated to the wrap of cable developing upon the drum.

2. A level-wind structure according to claim 1 in which the carriage comprises a jib journaled intermediate its ends for swing movement about an axis removed a substantial distance from the drum normal to the axis of the drum, and having upon its two ends a respective one of two fair-lead sheaves carried for independent swivel motion about the center of the jib as an axis.

3. A level-wind structure according to claim 2 in which the jib is hollow and swivels bodily with one of the sheaves.

4. A level-wind structure according to claim 2 in which the jib is hollow with its journal comprised of a ball-andsocket joint permitting universal swing motion of the jib, the guide for the carriage comprising a stiff-arm fulcrumed for swing movement about an axis paralleling the rotary axis of the drum.

5. A level-wind structure according to claim 1 in which the motor is a double-acting hydraulic jack.

6. A level-wind structure according to claim 1 in which the connection between the drum and the motion-transfer member includes a rotary cam moving through a half revolution as the drum takes the multiple turns necessary for one complete wrap of cable to be made on the drum.

7. A level-wind structure according to claim 1 in which the connection between the motion-transfer member and the carriage comprises a flexible line which is paid out and taken in, respectively, from and to the member, according as the member is moving in one or the other of its opposite directions of travel, and at a line speed approximating the speed at which the motor is moving the carriage, the connection between the motion-transfer member and the motor comprising a means which reflects speed differences as between the line and the carriage and responsively transmits a corrective speed-changing impulse to the motor.

8. A level-wind structure according to claim 7, a shoe being provided pivoted to the carriage at a point offset from the toe portion for swing movement about an axis normal to the direction in which the carriage moves and having a spring-biased catch pivoted to the toe portion and in the normal position of the shoe hooking under a lip formed upon the carriage, the end of said flexible line which connects with the carriage being trained over the shoe and connected with the free end of the catch, a pull upon the line in excess of a predetermined force retracting said catch from the lip, producing slack in the line as the freed shoe swings under force of said line pull.

References Cited UNITED STATES PATENTS 2,988,292 6/1961 Bliss 242-158.4 X 3,031,153 4/1962 Attwood et al 242158 3,039,707 6/1962 Beck et a1 242-1582 X FOREIGN PATENTS 836,411 6/1960 Great Britain. 836,412 6/ 1960 Great Britain.

STANLEY N. GILREATH, Primary Examiner US. Cl. X.R. 254- 

